1. Field of the Invention
The present invention concerns a device for connecting a varistor or a resistor or an arrangement comprising a resistor and a varistor in parallel with the contacts of a circuit-breaker when the latter is opened and closed, the varistor or the resistor or the arrangement thereof being disposed inside the casing containing the interrupting chamber of the circuit-breaker.
2. Description of the Prior Art
British patent application 2 032 180 discloses a circuit-breaker comprising, inside the interrupting chamber, auxiliary contacts for inserting a capacitor into the circuit for a limited period after the contacts of the circuit-breaker separate. To this end a hook retains the auxiliary contacts against the action of a compressed spring; retraction of the hook releases the spring which opens the auxiliary contacts. At the end of the maneuver the spring is compressed again by an arm joined to the main mobile contact of the circuit-breaker.
A device of this kind is bulky and complex, which increases the cost of the equipment because of the need to increase greatly the volume of the interrupting chamber; a device of this kind is heavy and increases the energy required to operate the circuit-breaker; a device of this kind includes a spring which is compressed when the circuit-breaker is open, with the risk of unintentional closure of the device, which severely compromises safety.
An object of the invention is to provide a simple device adapted to be installed on existing circuit-breakers without significantly increasing their unit cost and, in particular, adapted to be accommodated in the casing of the interrupting chamber without increasing its size; another object of the invention is to provide a lightweight device which does not require any increase in the circuit-breaker operating energy; another object of the invention is to provide a device in which the spring is relaxed when the circuit-breaker is open, which enhances the safety of the device.
Another object of the invention is to provide a device enabling component insertion for a sufficient time after the arc contacts separate when the circuit-breaker opens to reduce effectively the breaking voltage surge.
The device necessarily comprises two contacts which separate after insertion; another object of the invention is to provide an inserter device which, after the insertion time, effects fast de-insertion in such a way as to interrupt the residual arc without difficulty.
Another object of the invention is to provide an inserter device which, despite relative displacement of its component parts at high speeds, includes damper means to prevent any jerkiness of operation.
Another object of the invention is to provide a device enabling component insertion when the circuit-breaker opens and also, if the user requires, when the circuit-breaker closes.